In such type of dumping toy truck, a dumping mechanism arranged in a car body has been operated to lift a rear deck through a lifting rod. However, since the lifting rod retractably protrudes from the car body by means of gears rotatable in the mechanism, some oscillating movement must be accommodated in addition to straight movement. In order to absorb the oscillating movement and to ensure smooth operation, the lifting rod is passed through an oblong or oval hole provided in an upper wall of the car body. Such hole having a larger size than a diameter of the lifting rod, there may also pass therethrough dust and gravel when used under bad conditions, which may be deposited on the inner dumping mechanism to obstruct the smooth operation and to cause damage of the mechanism. When the toy truck is handled by an infant, on the other hand, the rear deck may be sometimes obstructed for its lifting movement, thereby to damage operating gears of the mechanism and to disorder delicate adjustment of various components. Such malfunction of the mechanism results in a short-life and uninteresting toy.
Accordingly, an object of the invention is to provide a damping mechanism which is able to tightly seal a hole for passing the lifting rod for preventing invasion of dust and gravel, eliminating damage and disorder of the mechanism, and thus achieving smooth operation.
Another object of the invention is to provide a damping mechanism which is able to alleviate sudden shocks upon the lifting movement of the deck for preventing damage of inner gears and their adjustment, and thus achieving smooth operation.